Hack-saw frame



MayZl, 1929. ,L,LUFK|N 713,972

HACK SAW FRAME Filed. March 2, 1928 avwento'c Jay/v JLuF/r/N PatentedMay 21, 1929.

I UNITED STATES PATENT OFFICE.

JOHN L. LUFKIN, or NEW YORK, N. Y.,,assrenon TO THE nneru'nnnmernonuc'rs I conroanrron, me, on NEW YORK, N. Y., A CORPORATION or newYORK...

HACK-SAW FRAME.

- Application filed March 2,

The invention is directed particularly to the providing of a hack sawframe or holder which can be safely and efficiently used in electricalwork, though it may also be used 5 in other classes of work.

The accompanying drawings illustrate an embodiment of the invention.

Fig.'1 is a side elevation partly in section;

*Fig. 2 is an underside plan view F ig. 3 is an oblique plan showing theadjusting nut.

In electrical work, especially in cable cutting in underground manholes,the usual metal frame for hack saws is dangerous because of itselectrical" conductivity. Such cable cutting is often done while thecables are alive with several thousand volts.

The

workmen use rubber gloves and they'sometimes wind the adjacent parts ofthe metal handle with rubber and use various other makeshifts to avoidaccidental metal contact.

The present invention is designed particularly for this class of work.It provides a frame which is not only of an insulating character but hasvarious other advantages referred to hereinafter. I

The back 1 of the frame is a fairlyheavy rectangular strip of woodhaving an outer end 2 extending downward and a hand-grip 3 eX- tendingobliquely backward and downward. The portion between the back and thegrip is provided with an upward projection 1 and a downward projection5. The intermediate portion 6, which we may call the inner end of theframe, is diagonally bored to form a long square hole 7 and an enlargedround hole 8. A squared holder 9 lies in the portion 7 and has at itslower end a projecting portion 10 in which is fixed a backwardly bentpin 11 engaging a hole in the inner end of the blade 12. The outer endof the bladeholder 9 is threaded and engaged by a round nut 13 lying inthe lower part of the recess 8 and slotted on its outer end forengagement by a screw driver some distance below the top of the opening.The opposite end of the blade 12 has a hole which is engaged by a hook14 having a forward projection 15 lying in a slot 16 in the outer end 2of the frame and having an upwardly bent end 17 which is driven into arecess in the holder and is barbed to prevent it moving downward out ofthe recess.

To insert a new The blade is turning up the nut 13. lade the nut isturned 1928. Serial 1x01258454;

backward to permit pulling the holder 9 downward sufficiently for thepurpose.

The downwardly projecting outer end 2 of the frame is strengthened by adowel 18 extending upward through the central portion. The frame is madeof hard close-grained tough wood, such, for example, as ash. The grainof the wood extends lengthwise. It is then treated with a specialfilling and insulating hard varnish which serves two purposes. Itprevents the wood from absorbing moisture or any of the liquids whichare encountered and thus preserves its insulating quality. I H I The"hard varnishlargely prevents copper, iron orlead or other metal chipsandparticles from becomingembedded in the wood, which would tend toprovide a conducting medium.

The entire frame is: made of a single piece of wood of uniform lateralthickness of sufficient cross-section to provide a frame which isstiffer than the usual steel frame. Experionce shows that with such aframe there is less breakage of the saw blade when cuttingstrandedcables, where the strands sometimes bind and gripthe bladeclosely, than with the usual steel frame.

The downwardly inclined handle 3 provides a very effective grip in adirection which experience has shown gives the greatest strength toresist breakage under the strains which are encountered in use. Theshoulders formed by the projections 4 and 5 at the forward end of thehandle prevent the operators hands from slipping forward and coming intocontact with the saw blade or the metal parts of the holder or the work.The depression of the butt 13 below the top surface of the holder alsoprevents accidental contact. The lower end 19 of the outer portion 2 ofthe frame projects below the far end of the blade. This and theunderhang of the rear projection 5 protect the blade from accidentalcontact with adjacent cables and other metal parts within the manhole.The projecting part 19 particularly prevents the saw from being pushedso far as to make contact with an additional cable or the like. Thecables are always arranged close together and it is important to avoid ametal contact between the cable which is being sawed and the one nextbeyond it.

Various other insulating materials than wood may be used for all or forparts of the frame; and the latter, though preferably made in a singlepiece, may be made of two or more pieces.

Various modifications may be made by those skilled in the art withoutdeparting from the invention as defined in the followingclaims.

What I claim is:

1. A hack saw frame made of wood cut away to form a back and projectedends with grain substantially parallel tothe back, a blade holding hookhaving a shank disposed at an angle to the hook portion and extendedupwardly into a depending end of the frame and reinforcing the same.

2. A hack saw frame made of insulating material having a back andprojected ends, and a blade holding hook located in a plane intermediateto extremity of said ends and said back, said hook having an angularshank portion which is embedded below the outer surfaces of said frameso as to avoid accidental contact with electric conductors. 3. A hacksaw frame made of wood cut away to form a back and projected ends withgrain substantially parallel to the back, a blade holding hook having ashank embedded in one of said ends and having its saw engaging portionin a plane intermediate the extremity of said one end and said back.

4. A hack saw frame made of wood cut away to form a back and projectedends with grain substantially parallel to the back, a blade holding hookhaving a shank embedded in one of said ends and a reinforcement dowel inthe end carrying said hook.

5. A hack saw.frame made of a single piece of wood cut away to form aback, projected ends and a rearwardly and downwardly projectinghand-grip a holder lying in a recess in the frame and secured to one endofrthe blade, the end of the holder to which the blade is secured lyingbetween said projected ends, and an adjusting nut engaging the oppositeend of said holder and located below the surface of the frame, and ablade holding hook having a shank embedded in one of the projected ends.7 i

6. A hack saw frame made of a single piece of stock, shaped to form aback, projected ends and a rearwardly and downwardly projectinghand-grip, a holder lying in a recess in the frame and having its bladeengaging end terminating between said projected ends and in a planeintermediate the extremity of said ends and said back. a

In witness whereof, I have hereunto signed my name.

JOHN L. LUFKIN.

